1. Field of the Invention
The present invention relates to a semiconductor integrated circuit employing a MOSFET (Metal Oxide Semiconductor Field Effect Transistor).
2. Description of the Related Art
In a semiconductor integrated circuit, a constant voltage circuit (reference voltage circuit) is employed in order to generate a constant voltage that does not fluctuate with fluctuation in the power supply voltage or fluctuation in the temperature. Patent documents 1 and 2 each disclose a constant voltage circuit employing MOSFETs. FIG. 1 is a circuit diagram which shows a configuration of a constant voltage circuit 200 according to a comparison technique. The constant voltage circuit 200 includes a first transistor M11 and a second transistor M12 sequentially stacked between the power supply terminal and the ground terminal. The first transistor M11 is configured as a depletion-type N-channel MOSFET, and is arranged such that the gate thereof is connected to the source thereof. The second transistor M12 is configured as an enhancement-type N-channel MOSFET, and is arranged such that the gate thereof is connected to the drain thereof. A comparatively stable reference voltage Vref is generated at a connection node N1 that connects the first transistor M11 and the second transistor M12.